A 3G network architecture defined by the 3rd generation partnership project (The 3rd Generation Partnership Project, 3GPP) in a wideband code division multiple access (Wideband Code Division Multiple Access, WCDMA) R4 standard mainly includes: a radio access network (Radio Access Network, RAN), a core network (Core Network), and a bearer network (Backbone). A generalized RAN includes an air interface (Air Interface) between a terminal and a base station, namely, a Uu interface, and an Iub interface between the base station and a base station controller. For transmission and bearing, a RAN generally refers to an aggregation network between the base station and the base station controller.
With the development of a mobile network from 2G to 3G, and then to a long term evolution (Long Term Evolution, LTE) technology, a mobile communication network evolves along a broadband, packet, and flattening direction, a mobile all Internet protocol (Internet Protocol, IP) (ALL IP) network becomes an irreversible tendency. The RAN also faces a transformation tendency from a conventional time division multiplex (Time Division Multiplex, TDM)/asynchronous transfer mode (Asynchronous Transfer Mode, ATM) RAN to an IP RAN. The IP RAN based on an IP/multi-protocol label switching (Multi-Protocol Label Switching, MPLS) packet data technology has a higher bandwidth, supports statistical multiplex of a data service, can better support a future broadband mobile service, and adopt a technology that is the same as that of an IP backbone network, and is more consistent and integrated with the backbone network, therefore, the IP RAN is widely applied. The IP RAN mainly includes: an access ring of a base station side, where the access ring is formed by ATNs or another type of devices and an aggregation ring formed by CXs or another type of devices. Usually, each device on the aggregation ring may be accessed by 10 to 20 access rings. Each access ring is formed by about 10 ATNs. Generally, two high-end CXs or another type of devices are placed on the aggregation ring as gateways and are connected to the core network. The ATN or another device on the access ring is referred to as a cell site gateway (Cell Site Gateway, CSG) or a multi-service transport gateway (Multi-Service Transport Gateway, MSTG). The CX or another type of device on the aggregation ring is referred to as a radio controller site gateway (RNC Site Gateway, RSG) or a multi-service aggregation gateway (Multi-Service Aggregation Gateway, MSAG). A device located on both the access ring and the aggregation ring is a core router (Provider Router) in an MPLS virtual private network (Virtual Private Network, VPN), namely, a P device; and another device located on the access ring or the aggregation ring is a provider edge (Provider Edge, PE) in the MPLS VPN.
In an IP RAN solution, according to different service types, an end-to-end pseudo wire (PW) or a layer 3 VPN (L3VPN) may be deployed between the PE on the access ring (namely, the CSG) and the PE on the aggregation ring (namely, the RSG) for bearing. The L3VPN and the PW generally traverse the network by using an MPLS traffic engineering (Traffic Engineering, TE) tunnel. Initially, the MPLS TE tunnel adopts a static and manual configuration method, where a typical MPLS TE tunnel needs about 10 orders, and efficiency of manual configuration for the MPLS TE tunnel is low, and a configuration amount is large. Therefore, an RFC 4972 (Routing Extension for Discovery of MPLS TE Mesh Membership) of the Internet engineering task force (Internet Engineering Task Force, IETF) defines a mechanism of discovering an MPLS TE mesh member (Mesh Membership) through routing extension, which provides a method for automatically establishing the MPLS TE tunnel.
In a solution provided by the RFC 4972, a PE in the network may be defined as a member of a specific mesh group (Mesh Group) (a device may belong to multiple Mesh Groups), and releases information of the Mesh Group to which the device belongs through an interior gateway protocol (Interior Gateway Protocol, IGP), and in this way, the device may discover a member of the MPLS TE network through the IGP, and an MPLS TE tunnel is established between member devices belonging to the same Mesh Group, so as to form a full mesh (Full Mesh) connection. Based on the foregoing description, in an IP RAN scenario, different PEs on the access ring and on the aggregation ring may be divided into a corresponding Mesh Group, a node of the MPLS TE network is automatically discovered through an IGP notification, and an MPLS TE tunnel establishment is automatically initiated, thereby alleviating the configuration amount of MPLS TE, and improving the configuration efficiency.
However, because the solution provided by the RFC 4972 is only applicable to establishment of the full mesh connection, in this way, an MPLS TE tunnel is also established between two PEs on the access ring (namely, two CSGs) which belong to the same Mesh Group. Actually, the mobile service is connected from the base station to the base station controller, that is, it is only needed to establish an MPLS TE tunnel between a PE on the access ring and a PE on the aggregation ring, but not needed to establish an MPLS TE tunnel between PEs on the access ring. Therefore, the RFC 4972 solution has a limitation in use.